Self-advancing mine and roof support systems



Sept. 22, 1970 WARD ETAL 3,530,490

SELF-ADVANCING MINE AND ROOF SUPPORT SYSTEMS Filed Sept. 23, 1968 5Sheets-Sheet 1 DERic A. sTAW Sept. 22, 1970 W RD ET AL 3,530,490

SELF-ADVANCING MINE AND ROOF SUPPORT SYSTEMS Filed Sept. 23, 1968 5Sheets-Sheet 3 nam A STAIN mi Sept. 22, 1970 E. WARD ET AL 3,530,490

SELF-ADVANCING MINE AND ROOF SUPPORT SYSTEMS Filed Sept. 23, 1968 5Sheets-Sheet 5 INVENTORS ERiC WARD DERIC A .STAiN BY United StatesPatent C US. Cl. 91-170 3 Claims ABSTRACT OF THE DISCLOSURE A hydraulicself-advancing mine roof support has hydraulic prop means and ahydraulic ram for advancing the support, said prop means and ram beingin a hydraulic system which includes fluid-flow control valves for therelease of pressure-fluid from the prop means and the supply ofpressure-fluid to the advancing ram for advancing the support and meansfor delaying operation of the advancing means to advance the support fora predetermined time with respect to the release of hydraulic fiuid fromthe prop means to free the support from between floor and roof to enableit to be advanced.

This invention is for improvements in or relating to self-advancing mineroof support systems in which each support is of the kind (hereinafterreferred to as the kind specified) having one or more pressure-fluidextensible props or legs by which it is secured between floor and roofand a pressure-fluid operated device for effecting its advancementtowards the mineral face as mineral is removed therefrom. Often, but notalways, this advancing device is a hydraulic ram which utilises themineral face conveyor or an adjacent support as an anchorage or abutmentfor the advance of the support.

In the longwall method of working mineral-bearing strata and utilising aroof support system comprising supports as just described, the followingsequence of operations takes place:

Stage 1.The coal winning machine removes a strip of coal or othermineral from the length of the face.

Stage 2.The face conveyor, which receives the mineral removed from theface, is advanced towards the newly exposed face.

Stage 3.Each roof support is lowered from its roofsupporting condition,advanced up to the conveyor and then reset to the roof. This phase issystematic, in the systems with which the present invention isconcerned, insomuch as each support is advanced, following the passageof the mineral winning machine, only after the completion or nearcompletion of the advancing and resetting cycle of an adjacent orneighbouring preceding support.

There are several known ways in which the lowering of the supports andtheir advance takes place.

For instance, there is what is known as the servo-lowering system inwhich an advancing ram or jack of the support is operable to advance thesupport only when the pressure in the roof-supporting props or legsreaches a predetermined figure. Should the roof-supporting structuremeet an obstruction the advance is delayed until further lowering of thesupport has been effected and it can clear the obstruction.

The servo-lowering system just described has the disadvantage of theroof support dragging along the mine roof and in so doing there is atendency for the props or legs of the support to be set in an attitudeleaning away from the mineral face. This is detrimental to proper roofsupport since natural convergence of the roof moves the 3,530,490Patented Sept. 22, 1970 props or legs in the same direction and there isset up an off-centre loading condition.

Another known method of support advance is to lower the prop or props ofthe support to a positive stop position and upon reaching this stopposition pressure is built up to actuate the advancing ram or otheradvancing device. This method has the disadvantage of slowing up theadvancement of the support since at each support there will be a delayuntil such support has been lowered to the predetermined height.

According to the present invention there is provided a mine roof supporthaving a fluid-operated prop or props and a fluid-operated advancingmeans which is inoperable until a predetermined time lapse has takenplace from the release of the fluid-pressure in said prop or props.

More specifically the present invention provides a mine roof supportsystem comprising a series of supports of the kind specified and inwhich lowering and advance of the supports in turn is initiated by thecompletion or near completion of the advance and resetting of apreceding support in the support series, wherein means is provided forautomatically delaying for a selectable period the start of advancementof the support with respect of the lowering thereof.

In other words, the means for delaying advance of the support until itsheight has been reduced by a predetermined amount is adjustable so thatthe delay may be varied to suit the prevailing conditions in the mine.For instance, a relatively long delay will be required where big roofsteps are likely to be encountered and a short delay where the roof isrelatively flat or only small roof steps are likely to be encountered.

One particular embodiment of the invention will now be described, by wayof example, with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic representation of the support and its valvemechanisms,

FIG. 2 is a side elevation of the support, and

FIG. 3 is a rear elevation.

Referring to FIG. 1 of the drawings, 10 indicates a hydraulicallyextensible prop or leg which it may be assumed constitutes a part of ahydraulic self-advancing mine roof support of known form. Such a supportis shown in FIGS. 2 and 3 and comprises, in addition to the props orlegs 10, a base 10a and a roof-engaging structure 1012 supported on theprops or legs 10'. A doubleacting hydraulic ram for advancing thesupport is indicated at 11 and is anchored to the support at 11a and hasa clevis 11b for anchoring its piston to a face conveyor. The ram 11 hasports 13 and 12 which serve as pressurefluid supply and exhaust portsaccording to whether the ram is being extended to, for example, pushover a mineral conveyor towards the mineral face or retracted so as toadvance the support up to the conveyor in the well known way.

The prop 10 is provided with a port 14 for the introduction anddischarge of pressure-fluid according to Whether the prop is beingextended to roof-supporting condition or lowered for the advance of thesupport.

The hydraulic system in which the prop 10 and ram 11 are connectedincludes two pilot-operated valves 15 and 16 and a metering or controlvalve 17 which can be adjusted as to the rate at which it will allowfluid to pass through it.

The pilot-operated valve 15 has a piston 18, a valve seat 20 and aspring-biassed sealing member or valve proper 22.

Similarly, the pilot valve 16 has a piston 19, a valve seat 21 and aspring-biassed sealing member or valve proper 23.

The pilot pistons 18 and 19 are fed with pressure-fluid via thepressure-fluid lines 24 and 25 respectively, the

3 pilot valves 18 and 19 controlling the flow of pressurefluid throughlines 26 and 27.

The pressure-fluid system of each support is connected to thepressure-fluid system of an adjacent or neighbouring preceding supportby a pressure-fluid line 28.

Assuming that the support is set in the roof-supporting condition andthe advancing device 11 has been fully extended, in other words, thesystem is at stage 2 referred to above.

A pressure-fluid signal is now transmitted, via the line 28. This signalmay be transmitted from a preceding sup port which has just completedits own advancing sequence and been reset between floor and roof. Thissignal acts immediately on the pilot piston 18 which depresses thesealing member 22 from the seat 20 and allows pressurefluid to pass fromthe hydraulic prop 10, via the port 14 and the seat 20 into the fluidline 26 and thence to exhaust. Thus, the support is lowered off to freeit from between floor and roof.

At the same time the pressure-fluid signal via the line 28 is meteredthrough the valve 17 and via the line 25 to the pilot piston 19. This,after a period of time which depends on the setting of the valve 17 andthe cubic capacity below the pilot piston, lifts the sealing member 23from the seat 21 and allows pressure-fluid to flow from the line 27through the port 12 to the retract side of the advancing ram 11. Theadvancing ram then operates to advance the support.

By adjustment of the metering valve 17 the operation of the advancingram 11, to advance its support, can be delayed for a long or short timeafter fluid from the supporting member 10 has been released. Thisensures that advance of the support will not commence until the member10 has been lowered sufiiciently to clear any steps in the roof. At thesame time the delay can be selected so that it is not unnecessarily longand therefore results in an objectionable slowing up of advancement ofthe supports as in the method previously referred to where advance of asupport is delayed until its props or legs have been lowered to apositive stop position.

It will be appreciated that with the above-described arrangement thetime delay depends on the time taken for fluid-pressure from the supply28, 25, to lift the piston 19 sufliciently to open the valve proper 23.This in turn depends on the amount of opening of the valve 17.

The arrangement whereby a hydraulic signal and hydraulic supply ispassed from one support to the next via the pipe lines 28 may, forexample, be similar to that described in our British patentspecification No. 1,038,262 and US. patent specification No. 3,320,001.

The valve 17 may be replaced by a constant flow device (e.g. an orificeof predetermined fixed size) in conjunction with a pilot valve 19 ofpredetermined cylinder volume and piston stroke.

The system may be introduced into any automatic or manual control systemwhere a delay is advantageous.

We claim:

1. A self-advancing mine roof support comprising a base, hydraulicallyextensible prop means mounted on said base and having inlet and exhaustmeans for pressure fluid, a roof engaging structure mounted on said propmeans for application thereby to a mine roof for the support thereof,hydraulic ram means connected to said support and having inlet andexhaust means for pressure fluid and operative, when connected to ananchorage, to advance the roof support, and a hydraulic pressure fluidsystem for said prop means and said hydraulic ram means, said systemincluding a source of pressure fluid, a pilot operated fluid controlvalve connected to said exhaust means of the hydraulic prop means forcontrolling the exhaust of pressure fluid therefrom, means connectingsaid valve and said source of pressure fluid whereby pressure fluid issupplied to said valve for the opening thereof, a further pilot operatedfluid control valve connected to the pressure fluid inlet means of theram means, means connecting said further control valve and said sourceof pressure fluid whereby pressure fluid is supplied to said ram meansunder the control of said further valve, means connecting said furtherValve and said source of pressure fluid whereby pressure fluid issupplied to said further valve for the opening thereof, and arestricting means in said means for connecting said further valve andsaid source of pressure fluid for restricting the flow of pressure fluidto said further valve and thereby delaying opening of said further valvewith respect to the opening of the valve controlling the exhaust ofpressure fluid from the prop means thereby to ensure release of thesupport from between room and floor of the mine working before it isadvanced.

2. A self-advancing mine roof support as claimed in claim 1, wherein therestricting means is an adjustable fluid metering valve.

3. A self-advancing mine roof support as claimed in claim 1, wherein atleast one of said pilot operated fluid control valves has a piston andis opened by the applica tion of said pressure fluid to said piston.

References Cited UNITED STATES PATENTS 2,585,297 2/ 1952 Beuscher.3,198,083 8/1965 Farr et a1. 9l461 3,357,313 12/1967 Pawling 91-452FOREIGN PATENTS 558,976 7/ 1957 Belgium.

PAUL MASLOUSKY, Primary Examiner Us. 01. X3.

